Engine spark timing control system

ABSTRACT

A mechanical device is located between the carburetor spark and intake manifold vacuum ports and the distributor breaker plate servo, the device containing two parallel flow circuits connected to the servo, one being connected to the spark port and containing an orifice, the other being connected to the intake manifold port and containing a servo operated valve that alternately blocks or unblocks the manifold vacuum application to the servo; the orifice providing slow changes in spark advance settings during light vehicle accelerations, and a rapid recovery upon subsequent momentary decelerations; the valve unseating during heavy accelerations to quickly lower the spark advance setting to avoid engine detonation.

[ 51 Oct. 17,1972

United States Patent Gropp Clark etal;.. l'23/ll7A i541 ENGINE SPARK TIMING CONTROL 7 SYSTEM [72] Inventor:

' Primary Examiner-Laurence Goodridge Karl Grosse Pomte Assistant Examiner-Cdrt-Flint Woods, Mich.

[731 Assignee: Ford Motor Company, Deal-born,

Attorney-John R. Faulkner and'Robert E. McCollum [57] ABSTRACT A mechanical device is located between the carburetor spark and intake manifold vacuum Mich.

ports and the distributor breaker plate servo, the device containing two parallel flow circuits connected to the servo, one

12 117 A being connected to the spark port and containing an "102p 5/06 orifice, the other being connected to the intake 0 7 n 9 u l u 9 m N8 h, m 0 u A 6 m.

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[58] Field OI manifld P and ntainin8 a Wanted valve that alternately blocks or. unblocks the manifold tm hbm m .lgu.l.a m m v ne 0 SC .mm. h pm ut msem o f vbc On a fic yn mu tflo mm 1cm umm m w ww am mom flnm d m mdm t Ci t..I O .2 80 m v np yka 8 0 ,1 n tmct a.mmn g C nv n vn lm i. wfi w a m% M c kng u cen U IUiia c hq-lv al l e VSVSda AAAA 7777 1111 .HHH 3 333 ,2222 ill..- m mmmm E ummh. e A t h t e .0 G P y n S nbk s E nC e 30 c T umr w ARSFM r. T k S e 9829 R m 6565 T 9999 m mwwm U 4987 9829 1 ,3 67l7 .l. 7226 "M 6 I 3232 6 Claims, 2 Drawing [Figures ENGINE SPARK TIMING CONTROL SYSTEM This invention relates, in general, to an engine spark timing control system. More particularly, it relates to an apparatus that provides good operating performance as well as fuel economy by not only quickly lowering the spark timing advance setting upon rapid vehicle accelerations, but also providing a rapid return to essentially the former setting upon mementary decelerations and return of the engine towards its former condition of operation.

This is an improvement over the spark timing control systems of the type shown in U.S. Pat. No. 3,606,871 and U.S. Pat. No. 3,638,626. The latter show a mechanical device in the vacuum line between a carburetor spark port and a vacuum servo to control the movement of the distributor breaker plate to advance or retard the engine spark timing setting. The device includes a one-way check valve and an orifice in parallel flow circuits. During rapid vehicle accelerations, the check valve unseats to provide a quick equalization of the pressure at the servo to the spark port vacuum, thereby lowering the spark advance setting to avoid detonation. Upon a momentary deceleration condition of operation, with a subsequent return towards its former operating condition, the orifice provides a slow buildup of the vacuum level at the servo to equal that at the spark port so that the advance setting only slowly returns to normal. This results in lower peak combustion temperatures and pressures and less emission of engine pollutants.

The above reference systems are poor for fuel economy. The slower spark advance buildup due to the ori-' fice bleed of vacuum causes late burning and generally at a point past optimum efficiency, i.e., into the expansion cycle of the engine.

This invention provides the advantageous functions described, plus a rapid return of the spark timing advance setting to essentially its former level, after a momentary deceleration, to improve the fuel economy.

More particularly, the invention includes a vacuum line between an intake manifold port and the distributor servo a spring operated, vacuum controlled valve in parallel flow relationship with a flow restriction in the vacuum line between the carburetor spark port and the distributor servo line.

The above construction permits a quick lowering of the servo port pressure level during rapid vehicle accelerations by unseating of the valve in response to lowered manifold vacuums. It also permits a rapid recovery of the spark timing advance setting upon a momentary deceleration and subsequent reacceleration towards its previous condition of operation, from a light acceleration mode of operation; the high manifold vacuum seats the valve, and the distributor servo vacuum decays only slowly through the orifice. Therefore, upon light reacceleration, the servo port pressure is near the previous level. This generally is close to or essentially the level that existed prior to the original vehicle acceleration, depending upon the duration of the deceleration.

Thus, the fast drop in spark timing advance setting, and subsequent return buildup delay built into the devices of.U.S. Pat. No. 3,606,871 and U.S. Pat. No. 3,638,626, is essentially eliminated during an operation of this type, resulting in a higher spark advance timing setting for the same time period, and greater fuel economy by more efficient operation.

It is a primary object of the invention, therefore, to provide an engine spark timing control apparatus that provides correct spark timing setting during rapid vehicle accelerations; and,from light acceleration modes, a rapid return to the correct setting after a momentary deceleration, for good engine performance and fuel economy purposes, while at the same time providing the other necessary and desirable changes in spark tirning to provide efficient engine operation.

Other objects, features and advantages of the invention will become more apparent upon reference to the succeeding detailed description thereof, and to the drawings illustrating a preferred embodiment thereof; wherein,

.FIG. 1 schematically illustrates a partial cross-sectional view of an engine spark timing system embodying the invention; and

FIG. 2 graphically illustrates different operating conditions of the spark timing system shown in FIG. 1.

FIG. l shows, schematically, only those portions of an internal combustion engine that are normally associated with the enginedistributor' spark timing setting control; such as, for example, a carburetor 10, a distributor breaker plate 12, a vacuum servo 14 to control the movement of breaker plate 12, and a line 16 connected between the carburetor and vacuum servo to automatically change the engine spark timing setting as a function of changes in engine vacuum spark port setting.

More specifically, carburetor I0 is shown as being of the downdraft type having the usual air-fuel induction passage 18 with an atmospheric air inlet 20 at one end and connected to the engine intake manifold 22 at the opposite end. Passage 18 contains the usual fixed area venturi 24 and a throttle valve 26. The latter is rotatably mounted on a part of the carburetor body across passage 18 in a manner to control the flow of airfuel mixture into the intake manifold. Fuel would be in ducted in the usual manner from a nozzle, not shown, projecting into or adjacent venturi 24, in a known manner.

Throttle valve 26 is shown in its engine idle speed position essentially closing induction passage 18, and is rotatable to a nearly vertical position essentially unblocking passage 18. A spark port 28 is provided at a point just above the idle position of throttle valve 26, to be traversed by the throttle valve during its part throttle opening movements. This will change the vacuum level in spark port 28 as a function of the rotative position of the throttle valve, the spark port reflecting essentially atmospheric pressure in the air inlet 20 upon closure of the throttle valve. An intake manifold vacuum sensing port 30 is also provided, for a purpose to be described.

As stated previously, the distributor, not shown, includes a breaker plate 12 that is pivotallymounted at 31 on a stationary portion of the distributor, and movable with respect to cam 32. The latter has six peaks 34 corresponding to the number of engine cylinders. Each of the peaks cooperates with the follower 36 of a breaker point set 38 to make or break the spark connection in a known manner for each one-sixth, in this case, rotation of cam 32. Pivotal movement of breaker plate 12 in a counterclockwise spark retard setting direction, or in a clockwise spark advance setting, is provided by an actuator 40 slidably extending from vacuum servo 14.

Servo 14 may be of a conventional construction. It has a hollow housing 42 whose interior is divided into an atmospheric pressure chamber 44 and a vacuum chamber 46 by an annular flexible diaphragm 48. The diaphragmis fixedly secured to actuator 40, and is biased in a rightward retard direction by a compression spring 50. Chamber 44 has an atmospheric or ambient pressure vent, not shown, while the chamber 46 is connected by a bore, not shown, to line 16.

During engine-off and other operating conditions to be described, atmospheric pressure exists on both sides of the diaphragm 48, permitting spring 50 to force the actuator 40 to the lowest advance or a retard setting position. Application of vacuum to chamber 46 moves diaphragm 48 and actuator 40 toward the left to an engine spark timing advance position, by degree as a function of the change in vacuum level.

Turning now to the invention, the vacuum line 16 consists of two branches S4 and 56 in parallel flow relationship. The branch 54 is adapted to be blocked or unblocked by a movable power operated valve 58. The latter is operatively fixed to the annular flexible diaphragm 60 of a vacuum controlled servo 62. The servo is essentially conventional, and includes a hollow housing divided by the diaphragm 60 into an atmospheric or ambient pressure chamber 64, and a vacuum chamber 66. Chamber 64 is connected to atmosphere by a hole 68, while chamber 66 is connected to intake manifold sensing port 30 by a passage 70. A spring 72 normally biases diaphragm 60 and valve 58 off its seat 74.

Communication between the spark port 28 and branch 56 is through a line 76 containing a sintered metal orifice 78.

The sintered orifice 78 is constructed of randomly oriented and dispersed multitudes of minute metal particles that are bonded together to form labyrinthian type fluid passages connecting the voids between particles.

As will be clear, an intake manifold vacuum force in line 70 higher than the force of spring 72 will seat valve 58 and cause the changes in the breaker plate setting to be made only slowly via orifice 78, as a function of light acceleration changes and decelerations by means of throttle valve 26. A lower manifold vacuum force will effect unseating of valve 58 and permit a quick equalization of the pressure levels between the manifold and servo chamber 46, to quickly lower the advance setting to avoid detonation.

Although only a single diaphragm servo 14 is illustrated, it will be clear that it is within the scope of the invention to connect line 16 to the primary or advance chamber of a dual diaphragm servo, such as is shown, for example, in FIG. 2 of Ser. No. 858,567, Kittredge, Dual Diaphragm Distributor, filed Sept. 1 l, 1969, and having a common assignee.

In operation, prior to starting the engine, the servo chambers 44 and 46, and 64 and 66 are equalized and essentially at atmospheric pressure. The diaphragm 60 and valve 58 are held away from the seat 74 by the spring 72, and passage 70 thereby completes a circuit from the intake manifold to the servo chamber 46 through passages 54 and 16.

When the engine is started, a momentary vacuum signal is applied to the distributor servo chamber 46 until the intake vacuum signal becomes strong enough to move the diaphragm onto its seat, sealing off opening 54. While the engine is idling, however, the vacuum signal trapped in the line 16 and servo chamber 46 is quickly destroyed by metering air at atmospheric pressure through the restriction 78 from the spark port 28. This characteristic has only a negligible effect on engine performance, however.

When the vehicle is subjected to light or gradual accelerations, the relatively high intake vacuum in line 70 holds the diaphragm 60 on its seat 74; therefore, the

rate of evacuation of the distributor servo chamber 46 is controlled by the restriction 78 in passage 76. This in turn controls (delays) the rate of spark advance.

As the vehicle decelerates, the intake vacuum at the manifold 22 is at a high level, and continues to keep the diaphragm 60 and valve 58 on its seat. With the throttle plate closed, the spark port 28 is exposed to an essentially atmospheric pressure. The flow of air, which destroys the distributor servo chamber 46 advance signal, is then controlled by the metering restriction 7 8. This in turn allows for a gradual reduction of spark advance.

The controlled decay of the spark advance signal, on deceleration, offers yet another advantage. When the vehicle is operating at a steady state speed and is sub- 30 jected to a momentary deceleration, the spark advance signal has only been'partially destroyed. The high intake manifold vacuum has. maintained valve 58 seated so the decay of vacuum in servo chamber 46 can occur only slowly through orifice 78. Then, on a light reacceleration, the spark signal will still be near the desired position for this particular speed and load. This minimizes depreciation of fuel economy.

When the vehicle is operating at steady state speeds and is suddenly subject to a heavy or wide open throttle acceleration, the intake manifold vacuum drops, which permits spring 72 to move the diaphragm 60 and valve 58 and open passage 54. This action then permits an unrestricted flow of air at atmospheric pressure towards the distributor servo chamber 46 and returns the spark setting to the normal lower position for that particular speed and load condition to prevent engine detonation.

FIG. 2 represents the various operations of the invention. The line AB illustrates the slow buildup of vacuum at the distributor servo by means of the orifice 78 and seating of valve 58. The line BD represents the quick decay in distributor servo chamber 46 vacuum to essential atmospheric pressure upon unseating of valve 58 during rapid vehicle accelerations to quickly lower the advance setting. Line GH represents the slow return to advance setting upon gradual release of the accelerator pedal from the rapid condition. Of course, this line will move up as a function of the degree of depression of the accelerator pedal during rapid accelerator pedal during rapid accelerations.

Line BC represents the slow I decay in advance chamber 46 vacuum during vehicle decelerations. The high manifold vacuum seats valve 58 and allows decay only slowly through orifice 78. if reacceleration occurs before a total decay in vacuum, such as at point E, the advance setting quickly returns to its former setting, at point F.

tion to return to or towards the previous setting provides a rapid recovery of the distributor breaker plate to essentially its former setting.

lclaim:

l. A spark timing control system comprising, an engine carburetor having an induction passage containing a spark port located above the idle speed position of a throttle valve controlling flow through the passage and subject to the depression in the carburetor as a function of the movement of the throttle valve from its idle speed position, an engine distributor having a breaker plate pivotally movable in opposite directions to advance and retard the spark timing, an engine manifold vacuum port, first vacuum controlled servo means connected to said breaker plate for moving the same, slowfast flow rate control means between said spark port and servo means to control the rate of change of application of vacuum from said spark port to said servo means, said control means including flow restriction means operable in response to light accelerations indicated by gradual vacuum level increases at said spark port occasioned by gradual throttle valve openings for slowly applying the vacuum increase to said servo means to slowly advance the engine spark timing, said flow restriction means also being operable in response to engine deceleration conditions indicated by a decaying vacuum level at said spark port occasioned by closing throttle movements for delaying the decay of vacuum at said servo means to slowly lower the engine spark timing advance setting, and second vacuum controlled on-off valve means operable in response to sudden accelerations indicated by a rapid decay of spark port and manifold vacuums occasioned by fast throttle openings to open and quickly decay the servo means vacuum to quickly lower the spark timing advance setting to minimize detonation.

2. A control system as in claim 1, including conduit means connected at one end to said servo means and being branched at its other end with one branch connected to said spark port and a second branch connected to said manifold port, said spark port branch containing an orifice constituting said flow restriction means, said second branch containing said second vacuum controlled means.

3. A control system as claim 2, said second vacuum controlled means comprising a second vacuum servo means having a flexible diaphragm dividing said latter servo means into a chamber connected to atmospheric pressure and a chamber interposed in said second branch connected at one portion to said intake manifold port and at another portion to said first servo means, said diaphragm in a first position operatively blocking said second branch in response to intake IEaIIifOIdVgCULIm above a predetermined level acting t ereon, w ereby the change in rate of application 0 vacuum to said distributor servo means is controlled by said orifice, and-spring means biasing said diaphragm to a second position unblocking said second branch.

4. A control system as in claim 2, said second vacuum controlled means including a valve movable in said second branch between a flow blocking position in response to intake manifold vacuum above a predetermined level operatively acting thereon and a position unblocking said second branch, and spring means for moving said valve to said flow unblocking position.

5. A control system as in claim 4, said second vacuum controlled means including a second vacuum servo having a power actuated member connected to said valve and actuated in response to changes in said intake manifold vacuum.

6. A spark timing control system comprising, an engine carburetor having an induction passage containing a spark port located above the idle speed position of a throttle valve controlling flow through the passage and subject to the depression in the carburetor as a function of the movement of the throttle valve from its idle speed position, an engine distributor having a breaker plate pivotally movable in opposite directions to advance and retard the spark timing, an engine manifold vacuum port, first vacuum controlled servo means connected to said breaker plate for moving the same, slowfast flow rate control means between said ports and servo means to control the rate of change of application of vacuum from said spark. port to said servo means, said control means including conduit means connecting said manifold vacuum port and said spark port in branch parallel flow paths to said servo means, said spark port branch containing an orifice delaying the application of the change of pressure level at said spark port to said servo means, said manifold vacuum branch containing a servo operated valve blocking said manifold vacuum branch at higher manifold vacuums above a predetermined level so that changes in engine spark timing are controlled by the time delay of said orifice, said valve at lower manifold vacuums operatively unblocking said manifold vacuum branch to rapidly equalize the first servo means pressure level to the intake manifold vacuum level whereby said spark timing setting is rapidly lowered. 

1. A spark timing control system comprising, an engine carburetor having an induction passage containing a spark port located above the idle speed position of a throttle valve controlling flow through the passage and subject to the depression in the carburetor as a function of the movement of the throttle valve from its idle speed position, an engine distributor having a breaker plate pivotally movable in opposite directions to advance and retard the spark timing, an engine manifold vacuum port, first vacuum controlled servo means connected to said breaker plate for moving the same, slow-fast flow rate control mEans between said spark port and servo means to control the rate of change of application of vacuum from said spark port to said servo means, said control means including flow restriction means operable in response to light accelerations indicated by gradual vacuum level increases at said spark port occasioned by gradual throttle valve openings for slowly applying the vacuum increase to said servo means to slowly advance the engine spark timing, said flow restriction means also being operable in response to engine deceleration conditions indicated by a decaying vacuum level at said spark port occasioned by closing throttle movements for delaying the decay of vacuum at said servo means to slowly lower the engine spark timing advance setting, and second vacuum controlled on-off valve means operable in response to sudden accelerations indicated by a rapid decay of spark port and manifold vacuums occasioned by fast throttle openings to open and quickly decay the servo means vacuum to quickly lower the spark timing advance setting to minimize detonation.
 2. A control system as in claim 1, including conduit means connected at one end to said servo means and being branched at its other end with one branch connected to said spark port and a second branch connected to said manifold port, said spark port branch containing an orifice constituting said flow restriction means, said second branch containing said second vacuum controlled means.
 3. A control system as in claim 2, said second vacuum controlled means comprising a second vacuum servo means having a flexible diaphragm dividing said latter servo means into a chamber connected to atmospheric pressure and a chamber interposed in said second branch connected at one portion to said intake manifold port and at another portion to said first servo means, said diaphragm in a first position operatively blocking said second branch in response to intake manifold vacuum above a predetermined level acting thereon, whereby the change in rate of application of vacuum to said distributor servo means is controlled by said orifice, and spring means biasing said diaphragm to a second position unblocking said second branch.
 4. A control system as in claim 2, said second vacuum controlled means including a valve movable in said second branch between a flow blocking position in response to intake manifold vacuum above a predetermined level operatively acting thereon and a position unblocking said second branch, and spring means for moving said valve to said flow unblocking position.
 5. A control system as in claim 4, said second vacuum controlled means including a second vacuum servo having a power actuated member connected to said valve and actuated in response to changes in said intake manifold vacuum.
 6. A spark timing control system comprising, an engine carburetor having an induction passage containing a spark port located above the idle speed position of a throttle valve controlling flow through the passage and subject to the depression in the carburetor as a function of the movement of the throttle valve from its idle speed position, an engine distributor having a breaker plate pivotally movable in opposite directions to advance and retard the spark timing, an engine manifold vacuum port, first vacuum controlled servo means connected to said breaker plate for moving the same, slow-fast flow rate control means between said ports and servo means to control the rate of change of application of vacuum from said spark port to said servo means, said control means including conduit means connecting said manifold vacuum port and said spark port in branch parallel flow paths to said servo means, said spark port branch containing an orifice delaying the application of the change of pressure level at said spark port to said servo means, said manifold vacuum branch containing a servo operated valve blocking said manifold vacuum branch at higher manifold vacuums above a predetermined level so that changes in engine spark timing are controlleD by the time delay of said orifice, said valve at lower manifold vacuums operatively unblocking said manifold vacuum branch to rapidly equalize the first servo means pressure level to the intake manifold vacuum level whereby said spark timing setting is rapidly lowered. 